Organisms from cyanobacteria through vertebrates make use of biochemical
and genetic oscillators to drive repetitive processes like cell cycle
progression and vertebrate somitogenesis. Despite the complexity and
diversity of these oscillators, their core design is thought to be shared.
Notably, most of them contain a core positive-plus-negative feedback
architecture. Here we use the early embryonic mitotic cycles in *Xenopus* as
a motivating example and discuss how the positive feedback functions as a
bistable switch and the negative feedback as a time-delayed, digital switch
(Yang and Ferrell, Nat Cell Biol, 2013; Ferrell, Tsai, and Yang, Cell,
2011). I will next discuss our ongoing and future research projects on
essential biological clocks in early embryos. We employ mathematical
modeling, microfluidic techniques, and optical imaging for a quantitative
understanding of self-organizing behaviors of single cells and single
molecules during early embryo development. Interested students are
encouraged to contact me and to visit our webpage for more details.